While the scene containing the target object is represented by a single-channel heightmap \(\mathbf {s} \in \mathbb {R}^{H \times W}\) , end effectors are represented by a 4-channel map \(\mathbf {e} \in \mathbb {R}^{H \times W \times 4}\) . \(\mathbf {e}\)  represents 2 states of the end effector in which each state corresponds to a pair of channels. This is especially useful for grasping, in which the 2 states refer to the open and closed configuration of the gripper [1]}. Examples are shown in fig:ee.
